Merck to buy antibody-drug conjugate developer VelosBio

Merck & Co. will pay $2.75 billion to acquire the private San Diego–based cancer firm VelosBio, which is developing antibody drugs that target tyrosine kinase–like orphan receptor 1 (ROR1). VelosBio’s most advanced candidate is an antibody-drug conjugate (ADC) that targets ROR1—found on some cancer cells but not healthy adult cells—and unleashes a toxic agent called monomethyl auristatin E. Three approved ADCs use the same toxic agent. VelosBio began a Phase 2 trial of its ADC in October. The firm also has a preclinical bispecific antibody that targets ROR1 and recruits immune cells to destroy the tumor.